micro Flashcards
S. pneumoniae morphology, virulence factors, incubation
Gr+ diplococcus
capsule, IgA1 protease, pneumolysin
1-3 days
pneumolysin
cholesterol dependent cytolysin that lyses cholesterol-containing membranes -> inflammation -> inhibit complement and phagocytosis
S. pneumoniae transmission and treatment
oropharynx and nasopharynx -> autoinnoculation (endogenous) esp in winter / early spring
risk factors: recent RT infx
cephalosporin, fluoroquinolone, or vancomycin
vaccine preventable
S. penumoniae lab
catalase - alpha hemolytic optochin sensitive bile-soluble (only strep that is) quellung reaction + facultative anaerobe latex agglutination + blood or chocolate agar
S. pnumoniae diseases
pneumonia (vaccine preventable)
otitis media, bacteremia, sepsis, meningitis
diseases caused by host response!
GBS morphology, virulence factors, incubation
Gr+ cocci clusters
capsule, adhesive pili,
early onset <7 days or late 7-90 days
GBS transmission and treatment
commensal in GI and GU; only harmful in pregnant women and transmitted through vaginal delivery
newborns, elderly, immunocompromised, and pregnant women at risk
penicillin, intrapartum anabiotic prophylaxis
GBS lab
catalase - beta hemolytic bacitracin resistant CAMP + hippurate test positive
GBS diseases
baby strep, miscarriage / stillbirth / preterm delivery, bacteremia, meningitis, NJIs, STIs, sepsis
N. meningitids morphology, virulence factors, incubation
Gr- diplococci facultative intracellular strict human pathogen
capsule (ABCW135Y) IgA1 protease, pili, OMPs, LOS, blebs, variation
3-7 days
N. meningitidis transmission and treatment
nasopharynx oral secretion in winter / early spring
infancy, adolescents, close quarters
penicilline; vaccine and chemoprophylaxis of close contacts
N. meningitidis lab
catalase +
oxidase +
ferments glucose (dextrose) and maltose, not sucrose and lactose
growth on blood or chocolate agar
N. m diseases
meningitis, bacteremia, non-blanching rash, disseminated intravascular coagulation syndrome (DIC), pneumonia, arthritis, urethritis
L. monocytogenes morphology, virulence factors, incubation
Gr+ bacillus (motile) facultative intracellular in macrophages, epithelium, and fibroblasts listerolysin O (LLO), ActA, Internalin 3-70 days
Listeria transmission and treatment
food, soil, human GI; in summer
newborns, elderly, immunocompromised, pregnant women
penicillin + gentamicin
Listeria lab
catalase + weak B hemolysis CAMP + sugar fermenting tumbling motility in CSF grows at refrigerated temps
Listeria diseases
flu-like symptoms, miscarriage / stillbirth / premature delivery, neonate meningitis, septicemia
or self-limited gastroenteritis
CAMP test
enhanced hemolysis in the presence of Staph. aureus
hippurate test
purple color = hippurate hydrolysis
internalin
listeria endocytosis invasion into host cells
LLO
listeria creates pores to exit cells
ActA
actin comet tails
polymerizes actin behind bacteria to push through cytoplasm or plasma membrane
Hib morphology, virulence factors, incubation
Gr- bacillus
IgA1 protease, capsule, LOS
‘a few days’
Hib transmission and treatment
direct contact or respiratory droplets in Sept - Dec, Mar - May
infants, children < 5, elderly, immunocompromised
amoxicillin or generation 2, 3 cephalosporin
vaccine and chemoprophylaxis of close contacts
meningitis / encephalitis
meningitis - blood-CSF barrier, meninges infx
encephalitis - BBB barrier, cortex infx
causes of meningitis 0-4 weeks 4-12 weeks 3 months - 18 yo 18-50 yo >50, immunocompromised
E. coli, Listeria, GBS E. coli, GBS, S. pneumo, Hib, N. mening Hib, S. pneumo, N. mening Hib, S. pneumo, N. mening S. pneumo, N. mening, Listeria, Gr- aerobic bacilli
